Attentional Modulation Of Correlation Of Hemodynamic Responses Between Domains In Monkey V4

Our retinas receive a large amount of visual information at any given moment.The visual cortex,including the primary visual cortex(VI),secondary visual cortex(V2),and other extrastriate areas,processes visual information to recognize the contents of a visual scene.However,owing to the restricted capacity of our brain to process information,only a fraction of this incoming visual information can be adequately processed for behavioral purposes.Given this restriction,our brain uses attentional mechanisms to select behaviorally relevant information.The spatial attention mechanism allows us to focus on a certain position in the visual field for enhanced processing;focusing attention on a particular location in the visual field enhances the intensity of neuronal activities in the visual cortex associated with location.To better understand this aspect,several existing studies on visual attention have focused on the fourth visual area(V4),which is one of the extrastriate areas.A previous study reported that spatial attention enhanced a large-scale stimulus-nonspecific visual response but did not affect the column-scale stimulus-selective activities in monkey V4.In this study,we used intrinsic signal optical imaging methods,which is based on hemodynamic activity in the cortex,to investigate the attentional effect on the relationship among column-scale activities in V4.It was noted that spatial attention did not affect the correlation of hemodynamic responses among stimulus-selective regions.Instead,the attention enhanced the correlation of responses among "active domains," which are regions involving the occurrence of column-scale stimulus-nonspecific activities.The results suggest that attentional processes in V4 enhance the strength of the network connection among the task-related functional regions.This result provided a new thought to study the network connection in V4.